commit: 6b0b79d38806481c1c8fffa7c5842f3c83679a42
From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <[email protected]>
Date: Wed, 9 May 2012 13:53:22 +0200
Subject: USB: cdc-wdm: cannot use dev_printk when device is gone
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

We cannot dereference a removed USB interface for
dev_printk. Use pr_debug instead where necessary.

Flush errors are expected if device is unplugged and are
therefore best ingored at this point.

Move the kill_urbs() call in wdm_release with dev_dbg()
for the non disconnect, as we know it has already been
called if WDM_DISCONNECTING is set.  This does not
actually fix anything, but keeps the code more consistent.

Cc: Oliver Neukum <[email protected]>
Cc: stable <[email protected]>
Signed-off-by: Bjørn Mork <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/usb/class/cdc-wdm.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 7652275..90bc916 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -533,7 +533,9 @@ static int wdm_flush(struct file *file, fl_owner_t id)
        struct wdm_device *desc = file->private_data;
 
        wait_event(desc->wait, !test_bit(WDM_IN_USE, &desc->flags));
-       if (desc->werr < 0)
+
+       /* cannot dereference desc->intf if WDM_DISCONNECTING */
+       if (desc->werr < 0 && !test_bit(WDM_DISCONNECTING, &desc->flags))
                dev_err(&desc->intf->dev, "Error in flush path: %d\n",
                        desc->werr);
 
@@ -625,12 +627,13 @@ static int wdm_release(struct inode *inode, struct file 
*file)
        mutex_unlock(&desc->wlock);
 
        if (!desc->count) {
-               dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
-               kill_urbs(desc);
                if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
+                       dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
+                       kill_urbs(desc);
                        desc->manage_power(desc->intf, 0);
                } else {
-                       dev_dbg(&desc->intf->dev, "%s: device gone - cleaning 
up\n", __func__);
+                       /* must avoid dev_printk here as desc->intf is invalid 
*/
+                       pr_debug(KBUILD_MODNAME " %s: device gone - cleaning 
up\n", __func__);
                        cleanup(desc);
                }
        }
-- 
1.7.3.4
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